Wireless communications devices, such as wireless terminals or wireless base stations, include wireless transceivers to perform wireless communications, such as radio frequency (RF) communications. A wireless communications device can include a duplexer (or multiplexer) to allow simultaneous transmission and reception in different frequency bands using the same antenna while ensuring that relatively high power transmit signals transmitted by the wireless transceiver do not swamp relatively low power receive signals received by the wireless transceiver.
A duplexer has an antenna port (for connection to an antenna), a receive port (to receive a signal from the antenna port) and transmit port (to transmit a signal to the antenna port). A multiplexer has an antenna port and one or more receive ports and one or more transmit ports. Note that a duplexer is a type of multiplexer.
A duplexer or multiplexer can include bandpass filters implemented with acoustic-type resonators. Conventional duplexers/multiplexers including bandpass filters implemented with acoustic-type resonators have relatively limited maximum power handling capabilities, which can prevent use of such conventional duplexers/multiplexers in high-power, high-frequency applications, such as in Worldwide Interoperability for Microwave Access (WiMax) applications or Long-Term Evolution (LTE) applications. WiMax is based on the IEEE (Institute of Electrical and Electronics Engineers) 802.16 Standard (as amended by the IEEE 802.16e or IEEE 802.16e-005). WiMax is able to provide broadband wireless connectivity for mobile stations at relatively high data rates. LTE is a technology that provides an enhancement to the Universal Mobile Telecommunications System (UMTS) technology. LTE is described in 3GPP TS 23.401 and 23.402.
In conventional duplexers/multiplexers that employ bandpass filters with acoustic-type resonators, high-power and high-frequency communications can cause ultrasonic vibration in metallic electrodes of the acoustic-type resonators, which can lead to a phenomenon referred to as acousto-migration, in which metal grain boundaries in the resonators migrate. The acousto-migration phenomenon can reduce the lifetime of the filters. Therefore, such filters may not survive for a desirable length of time at desired power levels and frequencies that may be required in certain types of wireless networks.